ABB KORC series comprises high-performance current transformers

The ABB KORC series comprises high-performance secondary current transformers designed for use in low-voltage industrial applications. They are commonly applied in motor control centers (MCCs), variable speed drives (such as ABB ACS580, ACS880), capacitor banks, and power distribution systems. The KORC series is known for its compact construction, high accuracy, and reliable performance under demanding operating conditions.

Key Features

Compact modular design – suitable for space-limited installations

High short-circuit withstand capability – ensures safety and durability

Multiple saturation characteristics – linear, partly saturated, and fully saturated types available to meet different protection and metering requirements

Flexible mounting – can be installed directly on busbars or cables

Compatible with ABB and third-party systems – widely used as a replacement part in retrofit and maintenance projects

Product Classification

The KORC series is organized by frame size (4L, 4S, 5L, 5S) and secondary current behavior:

1. Secondary Linear Current Transformers (KORC 4L / 5L)

These transformers provide a linear response over a wide current range. They are suitable for measurement and linear protection applications where signal fidelity is critical.

Frame Rated Current Order Code

KORC 4L 185R/4 1SCA022193R7830

KORC 4L 235R/4 1SCA022193R7670

KORC 4L 310R/4 1SCA022181R0760

KORC 4L 400R/4 1SCA022193R8050

KORC 5L 375R/4 1SCA022207R0410

KORC 5L 500R/4 1SCA022208R1010

KORC 5L 650R/4 1SCA022208R1280

KORC 5L 850R/4 1SCA022208R1440

2. Secondary Partly Saturated Current Transformers (KORC 4S)

These are optimized for applications where moderate saturation is acceptable, often used in capacitor switching or non-critical protection circuits.

Frame Rated Current Order Code

KORC 4S 60R/4 1SCA022266R1790

KORC 4S 80R/4 1SCA022187R1800

KORC 4S 110R/4 1SCA022187R2010

KORC 4S 145R/4 1SCA022187R2280

3. Secondary Saturated Current Transformers (KORC 4S / 5S)

Fully saturated types are used in protection schemes where current limitation is required, such as short-circuit and overload protection in heavy-duty drives.

Frame Rated Current Order Code

KORC 4S 60R/4 1SCA022394R2740

KORC 4S 80R/4 1SCA022180R9750

KORC 4S 105R/4 1SCA022394R2820

KORC 4S 110R/4 1SCA022180R9910

KORC 4S 140R/4 1SCA022394R2910

KORC 4S 145R/4 1SCA022181R0170

KORC 4S 185R/4 1SCA022181R0330

KORC 4S 235R/4 1SCA022193R7410

KORC 4S 310R/4 1SCA022181R0500

KORC 4S 400R/4 1SCA022193R8210

KORC 5S 375R/4 1SCA022207R0670

KORC 5S 500R/4 1SCA022208R1610

KORC 5S 650R/4 1SCA022208R2090

KORC 5S 850R/4 1SCA022208R2250

4. Three-Phase Current Transformers (without terminal block)

For three-phase applications requiring compact, terminal-block-free installation, ABB also offers dedicated versions of the KORC series.

Secondary Linear (3-phase, no terminal block)

Frame Rated Current Order Code

KORC 4L 185/4 1SCA022142R2670

KORC 4L 235/4 1SCA022142R2830

KORC 4L 310R/4 1SCA022142R3050

KORC 4L 400R/4 1SCA022142R3210

KORC 5L 375R/4 1SCA022142R4290

KORC 5L 500R/4 1SCA022141R1980

KORC 5L 650R/4 1SCA022141R2100

KORC 5L 850R/4 1SCA022141R2360

Secondary Saturated (3-phase, no terminal block)

Frame Rated Current Order Code

KORC 4S 60/4 1SCA022266R9000

KORC 4S 80R/4 1SCA022176R7570

KORC 4S 105R/4 1SCA022292R9940

KORC 4S 110R/4 1SCA022142R1430

KORC 4S 140R/4 1SCA022293R0100

KORC 4S 145R/4 1SCA022142R1600

KORC 4S 185R/4 1SCA022142R1860

KORC 4S 235R/4 1SCA022142R2080

KORC 4S 310R/4 1SCA022142R2240

KORC 4S 400R/4 1SCA022142R2410

KORC 5S 375R/4 1SCA022142R3480

KORC 5S 500R/4 1SCA022142R3640

KORC 5S 650R/4 1SCA022142R3810

KORC 5S 850R/4 1SCA022142R4020

Popular and Widely Used Models

Based on real-world field applications, the most commonly used KORC models fall into the 185A – 400A range (KORC 4L / 4S). These are frequently found in:

Variable speed drives (90kW – 200kW)

Fan and pump control panels

General industrial motor control

For higher power applications (250kW – 400kW), the KORC 5L / 5S series (500A – 850A) is the standard choice, especially in heavy industries such as mining, extruders, and cranes.

Important Selection Notes

Linear vs. saturated types – Linear types are used for accurate measurement; saturated types are used for protection. They are not interchangeable.

R suffix – Indicates standard configuration; models without “R” may have different internal characteristics.

4L vs. 4S frame – 4L is linear; 4S is partly saturated or fully saturated depending on the subseries.

Terminal block – Some versions include a built-in terminal block; others require external wiring.

The ABB KORC series offers a complete range of secondary current transformers for low-voltage power systems. Whether you need high linearity for metering, saturation for protection, or a compact three-phase solution, the KORC series provides reliable, field-proven performance. Always verify the original part number and saturation type before replacement to ensure system compatibility.